The present disclosure relates to an impedance matching system and an operating method thereof.
In mobile communication terminals, an antenna circuit transmits or receives a certain radio wave signal through an antenna.
Impedance is required to be accurately matched such that the antenna has optimal transmission/reception irradiation performance.
Therefore, the antenna circuit includes a capacitor and an inductor. The antenna circuit controls the value of the capacitor and the value of the inductor to match the impedance of the antenna in an optimal state.
In the matching of impedance, the impedance of an antenna is matched in a state where a mobile communication terminal is located in a free space.
Generally, a user uses a mobile communication terminal in a state where the user holds a body with its hand and brings a speaker into contact with its ear, or uses the mobile communication terminal by using an earphone in a state where the body of the communication terminal has been placed in a bag or a pocket.
Since a user uses a mobile communication terminal in a state where the user has held a body with its hand and brought a speaker into contact with its ear or uses the mobile communication terminal in a state where the body of the communication terminal has been placed in a bag or a pocket, the impedance matching condition of an antenna varies, and consequently, the transmission/reception irradiation performance of the antenna with impedance matched in a free space is degraded.
Accordingly, mobile communication terminals include an adaptive tuning antenna circuit that allows an antenna to have optimal transmission/reception radiation performance by automatically controlling the impedance of the antenna when the impedance matching condition of the antenna is changed.
To optimally maintain the transmission/reception radiation performance of the antenna, the adaptive tuning antenna circuit is required to detect the changed impedance state of the antenna and change a value of a capacitor according to the changed impedance state.
However, since the related art cannot detect the characteristic of the capacitor that is changed according to the changed impedance state, the related art is required to detect a value of a capacitor for optimally maintaining the transmission/reception radiation performance of the antenna, and consequently, a time taken in matching an impedance is increased.